[U-Boot] [PATCH 1/4] mx7: psci: add cpu hotplug support

[Bryan O'Donoghue]

On 28/05/18 07:17, Anson Huang wrote:
> This patch adds cpu hotplug support, previous
> imx_cpu_off implementation is NOT safe, a CPU
> can NOT power down itself in runtime, it will cause
> system bus hang due to pending transaction. So
> need to use other online CPU to kill it when
> it is ready for killed.
> 
> Here use SRC parameter register and a magic number
> of ~0 as handshake for killing a offline CPU,
> when the online CPU checks the psci_affinity_info,
> it will help kill the offline CPU according to
> the magic number stored in SRC parameter register.
> 
> Signed-off-by: Anson Huang <Anson.Huang at nxp.com>
> ---
>   arch/arm/mach-imx/mx7/psci-mx7.c | 31 ++++++++++++++++++++++++++++---
>   arch/arm/mach-imx/mx7/psci.S     | 14 ++++++++++++++
>   2 files changed, 42 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/mx7/psci-mx7.c b/arch/arm/mach-imx/mx7/psci-mx7.c
> index 7dc49bd..6f69fd3 100644
> --- a/arch/arm/mach-imx/mx7/psci-mx7.c
> +++ b/arch/arm/mach-imx/mx7/psci-mx7.c
> @@ -77,12 +77,37 @@ __secure int imx_cpu_on(int fn, int cpu, int pc)
>   
>   __secure int imx_cpu_off(int cpu)
>   {
> -	imx_enable_cpu_ca7(cpu, false);
> -	imx_gpcv2_set_core1_power(false);
> -	writel(0, SRC_BASE_ADDR + cpu * 8 + SRC_GPR1_MX7D + 4);
> +	/*
> +	 * We use the cpu jumping argument register to sync with
> +	 * imx_cpu_affinity() which is running on cpu0 to kill the cpu.
> +	 */
> +	writel(~0, SRC_BASE_ADDR + cpu * 8 + SRC_GPR1_MX7D + 4);

Small suggestion. Make that "SRC_BASE_ADDR + cpu * 8 + SRC_GPR1_MX7D + 
4" into some sort of macro

#define imx_cpu_gpr_offset(cpu) \
	SRC_BASE_ADDR + cpu * 8 + SRC_GPR1_MX7D + 4

you use it several times so its a good candidate for functional 
decompisition IMO.

Also instead of having magic numbers - define them.

#define IMX_CPU_SYNC_ON ~0
#define IMX_CPU_SYNC_OFF 0

---
bod